There presently exist power tools specifically designed for driving drywall screws through a drywall panel into a receiving medium, such as a wooden stud, for securing the panel to the stud. The tool typically has a bit adapted to mate with the head of the screw, a depth gauge, a chuck for holding the bit, a clutch mechanism and a power unit. Normally the screw will be driven until the head is slightly below the surface of the panel, creating a "dimple" above the head which can be filled with drywall compound to hide the head from view. The clutch is usually preset to overrun at a specific torque and the torque is predetermined to be that required to drive the screw to the correct depth. When the clutch overruns, the operator knows that the screw has been driven properly.
In the majority of situations there is adequate clearance around the screws so that a power tool can be used in close proximity to the panel itself. There are other situations, however, where it is impossible to position the tool close to the panel and in such instances it becomes necessary to drive screws by hand or to use drywall nails. Such a situation can exist, for example, where there is ductwork near a ceiling and an adjacent wall, making it impossible to drive screws into a wooden header of the adjacent wall.
Also, when driving screws into ceiling panels in most rooms the operator has to stand on a scaffold or use stilts to position his body close enough to the ceiling to drive the screws.
The present invention has been designed to overcome the problem of driving screws, particularly drywall screws, in hard-to-reach areas and from the floor to the ceiling. The invention provides an extension which can fit between the clutch and the depth gauge or bit of a drywall "gun" as described above, thereby increasing the distance between the bit and the power head. This permits positioning of the bit in areas otherwise too small to accept the power head and also permits an operator to drive ceiling screws while standing on the floor. The extension device is provided as a plurality of sets of discrete elements so that any number of sets can be combined together in achieve the desired length of extension.
In one particular embodiment for one popular type of drywall gun the basic set includes a hexagonal drive rod receivable in the chuck of the tool in place of the original drive rod, a cylindrical sleeve having a hexagonal bore therethrough for receiving the replacement drive rod at one end and the original drive rod at the other end, and a cylindrical adaptor receiving the sleeve therein and bridging the gap between the chuck and the depth gauge of the tool. Since the depth gauge is normally threaded to the chuck the adaptor will have a female thread at one end for attachment to the chuck and a male thread at the other end for attachment to the depth gauge. If a further extension is required another basic set could be attached to the outer end of the first set and the depth gauge attached thereto rather than to the first set.
In another embodiment the replacement drive rod and the sleeve could be incorporated into a single moulded piece having a sleeve portion, a hexagonal projection at one end and a hexagonal bore at the other end. The projection of one sleeve portion would be matable with the hexagonal bore of an adjacent sleeve portion when multiple extensions are used.
Accordingly therefore, the present invention provides an extension device for increasing the distance between a power means and a bit means of apparatus for driving screws into a receiving medium, the apparatus including polygonal drive means connected to the power means and to the bit means, the device comprising: polygonal extension means connectable to the power means in place of the drive means; sleeve means for receiving the extension means at one end and the drive means at the other end thereof; and adaptor means for receiving the sleeve means therein and adapted to be connected to the power means at one end thereof.